Talk:Mechanical–electrical analogies

GA Review

This review is transcluded from Talk:Mechanical-electrical analogies/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Chiswick Chap (talk · contribs) 17:38, 15 March 2015 (UTC)

It's more than time that someone bravely agreed to review this fine but somewhat forbidding article. Fortunately it's so clearly and elegantly written that even my creaky old school physics had no trouble reading it through with the feeling that I was understanding it all. So here goes. Chiswick Chap (talk) 17:38, 15 March 2015 (UTC)

Rate	Attribute	Review Comment
1. Well-written:
	1a. the prose is clear, concise, and understandable to an appropriately broad audience; spelling and grammar are correct.	Prose: ok, though I did flicker over "one, unique"; copyright: spot checks all ok; spelling: ok; grammar: ok
	1b. it complies with the Manual of Style guidelines for lead sections, layout, words to watch, fiction, and list incorporation.	lead: ok Layout: ok; weasel: ok; fiction: n/a; lists: n/a.
2. Verifiable with no original research:
	2a. it contains a list of all references (sources of information), presented in accordance with the layout style guideline.	Clearly yes.
	2b. reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose).	They seem unimpeachable. Essentially everything is cited to solid textbooks. Spot checks all passed.
	2c. it contains no original research.	No sign of it.
3. Broad in its coverage:
	3a. it addresses the main aspects of the topic.	It gives the impression of covering the subject not just in main aspects but comprehensively. The structure (Impedance, Mobility and 'Through and across' analogies, each with translational, rotational and acoustical subsections) seems irreproachably solid.
	3b. it stays focused on the topic without going into unnecessary detail (see summary style).	Whole content is on-topic, and level of detail seems even and appropriate throughout.
	4. Neutral: it represents viewpoints fairly and without editorial bias, giving due weight to each.	No sign of any kind of commercial or other bias.
	5. Stable: it does not change significantly from day to day because of an ongoing edit war or content dispute.	No significant recent changes.
6. Illustrated, if possible, by media such as images, video, or audio:
	6a. media are tagged with their copyright statuses, and valid non-free use rationales are provided for non-free content.	The one and only image, by nom, is properly licensed.
	6b. media are relevant to the topic, and have suitable captions.	The image is relevant and captioned. I would like to see more in the way of illustration - a photo of Clerk Maxwell would be welcome, for instance. It occurred to me that it might be nice also to have an illustration of the analogy of pressure and volume flow rate with voltage and current, but this certainly isn't a requirement.
	7. Overall assessment.	It's a shame that Nickele, Firestone, Trent and Paynter are all represented only by redlinks: this says something about how much these engineering articles are helping to fill a gap in the encyclopedia. Of course these represent promising avenues for further work. Overall, I found the article admirably clear and well-constructed.

Origin of the Analogies

I would love to see a theoretical physics discussion of the origin of the analogy. On the surface, you could say we find it easy to think in terms of linear systems, so we think of components that act linearly. This leads directly to the same simple differential equations for different systems, especially when conservation of energy is a natural focal point for optimizing engineering applications. The most natural of the possible analogies is the impedance analogy which the one most commonly used and first cited in this article. The reason for this is that charge in electrical components is simply replaced with meters in the mechanical components. There are no other changes. Capacitors allow charge to build up for a fixed dielectric distance and the analogous spring allows meters to build up for a fixed number of charges (which are the source of resisting compression). For small compressions and non-saturating amounts of charge, both are linear. The same direct relation exists for inductors and mass: inductance (magnetism) from a classical view (pre-quantum) is a relativistic effect of charge build up per unit length, not a thing unto itself. See Schwartz, Feynman, and Wikipedia. For small changes, it is again linear so V=L*di/dt instead of having to resort to full-blown relativistic equations. So it seems mass could be viewed from a pre-quantum perspective as the relativistic effect of (quark?) charges being brought closer together as a result of length contraction. Again, it's linear for small changes in velocity so F=ma instead of using full-blown relativistic calculations. In short, linear electrical components control charge/length where length is held constant by the component, and mechanical systems do the same but hold the charge constant and allow lengths to change. This is simple enough that there should be some references out there that delve into the source of the analogies and thereby allow it to be included in the article. Ywaz (talk) 14:15, 5 November 2015 (UTC)

Analogy or analogies

Articles titles tend to use singular, and litterature seems to document an analogy, e.g. A new analogy between mechanical and electrical system elements. The article body uses both forms. Should we use singular or plural form?

I've renamed the article to use singular, but now I see it has passed GA review, so I'd like to get some opinions. (Context: I was actually busy in Wikidata to help someone to classify a Mason circuit as analogy). --Dereckson (talk) 10:27, 9 October 2019 (UTC)

I really think you should have opened this discussion first. I further think you should revert all that change. The article discusses a class of analogies and how they are related. It makes more sense to have a plural title. We make the dog article singular because all breeds of dog belong to the same species. The concept "dog" is one thing with all breeds being subsets and all individual dogs being elements of the same set. In the case of these analogies, the impedance analogy and the mobility analogy are not part of some greater theory we can call "mechanical-electrical analogy". On the contrary, they are separate and incompatible. It is done either one way or the other. Likewise the resistance–reluctance analogy is not compatible with the capacitance–permeance analogy. They are two entirely different ways of doing things. Your example (the Firestone paper) is referring to one particular analogy so of course it is singular. How is that relevant? Firestone repeatedly uses the plural in the paper when referring to analogies as a group.

By the way, what is this Mason circuit you mentioned? A circuit is not an analogy. SpinningSpark 11:17, 9 October 2019 (UTC)

@Dereckson: SpinningSpark 13:35, 10 October 2019 (UTC)

I've moved it back. Posted here, pinged, and e-mailed. No response in three days, not even to say you ate thinking about it and will reply later. SpinningSpark 14:51, 12 October 2019 (UTC)

Hamiltonians

Please can someone add to the Hamiltonians: 1/. The nomenclature 2/. An explanation - what the heck is being desdribed? — Preceding unsigned comment added by 2A00:23C4:1594:E600:49CE:1AC0:F728:8444 (talk) 14:58, 5 November 2020 (UTC)

The article currently states that,

The Hamiltonian variables, also called the energy variables, are those variables r = (q, p), which are conjugate according to Hamilton's equations.

What is lacking in that needs explaining?

As I originally wrote the article (and the state in which it passed GA), it did not contain Hamilton's equations at all. It had a much simpler statement, something along the lines that the Hamiltonian variables were those variables whose time derivative was the power conjugate variables. There is really no need to have Hamilton's equation in the article at all in my opinion. It does not really figure in constructing an analogy. I suggest reverting to the original format, but perhaps with an additional statement that the name derives from the variables' connection with Hamiltonian mechanics. The link to that article should be enough for anyone interested in that aspect. SpinningSpark 12:06, 23 November 2020 (UTC)

"The Hamiltonian variables, also called the energy variables, are those variables r = (q, p), which are conjugate according to Hamilton's equations.

What is lacking in that needs explaining?"

What r, q and p ARE would be a start !!!

I know this is probably a 'stupid' question, but this is Wikipedia, not a PhD level maths textbook.

For every equation, please give the nomenclature and examples with physical units. 51.219.114.246 (talk) 11:54, 10 July 2023 (UTC)

Physical implementations

I suggest adding a section on physical implementations of a mechanical-electrical analogy. I am aware of one mechanical system that provides a close analog to a wide range of electrical circuits: the toy Spintronics. As mentioned in the article, one of the main purposes of the mechanical-electrical analogy is to make an abstract topic more tangible, but it is not currently used this way in the article itself. Some pictures and a description of a real-life mechanical analogy could greatly benefit readers, hopefully making this fairly abstract article more tangible.

I have a big conflict of interest, so I hesitate to edit the article myself, but I'll provide as much material as I can for another editor interested in including it in this article. I'll be happy to answer questions. I'd also be happy to give a first pass at writing it. I'm not sure what the custom is for this sort of thing. Thanks!

Useful pictures:

• 
  The mechanical equivalent of an electronic oscillator circuit made using spintronic parts.
• 
  A spintronic ammeter. The pitch and volume of the sound it produces indicates the magnitude of current flow.
• 
  A spintronic 6 V battery. The battery puts a constant force (i.e., voltage) on the chain.
• 
  A spintronic 1 mF capacitor and voltmeter. A torsion spring on the inside stores energy when the sprockets on the body are turned.
• 
  A spintronic 55 H inductor. The spintronic inductor has three heavy weights attached to the outside of rotating sprockets. This makes the current change slowly when the voltage applied to it is changed abruptly.
• 
  A spintronic junction is the equivalent to an electrical junction (node) of three wires. Each sprocket behaves as one of the three wires. Despite the difference in diameter among the three sprockets, the planetary gear system makes them all behave equally.
• 
  The three spintronic resistors each have different equivalent values (from left to right): 1000 ohms, 500 ohms, and 200 ohms.
• 
  A spintronic equivalent of an enhancement-mode field-effect transistor. The greater the voltage applied to the top sprocket, the lower the resistance of the bottom sprocket.
• 
  This spintronic switch is a mechanical equivalent of a single-pole single-throw (SPST) toggle switch.

Useful references:

1. The Spintronics website and the Science of Spintronics page
2. A simulator of Spintronics
3. US application 2021343184A1, Paul Garrett Boswell, "Mechanical Analog of Electronics", published 2021-11-04 

Pgboswell (talk) 18:58, 4 August 2023 (UTC)